During the last 20 to 30 years, several biocompatible polymers have been developed for use in the body and approved for use by the U.S. Food and Drug Administration (FDA). These FDA-approved materials include polyglycolic acid (PGA), polylactic acid (PLA), Polyglactin 910 (VICRYL®), polyglyconate (MAXON®) and polydioxanone (PDS). Many other biocompatible polymers are under development. In general these materials biodegrade in vivo in a matter of months, although certain forms may biodegrade more slowly. These materials have been used in orthopedic applications, wound healing applications, and extensively as sutures. More recently some of these polymers have also been used in tissue engineering applications.
Tissue engineering is a field that develops tissue products that restore, maintain, or improve tissue function. The need for this approach has arisen out of the lack of suitable donor tissue to repair and restore the body.
In general there are three distinct approaches to engineer new tissue. These are 1) infusion of isolated cells or cell substitutes, 2) use of tissue inducing materials and/or tissue regeneration scaffolds (guided tissue repair) and 3) implantation of cells seeded in scaffolds.
In open scaffold systems and guided tissue repair, tissue engineering materials have normally been fabricated from natural protein polymers such as collagen or from synthetic polymers. These materials often do not have the specific mechanical requirements that a scaffold needs to provide until the new tissue is developed. These materials may also handle poorly, be difficult to suture or may not maintain the desired form or strength for a long enough period of time. Thus it is desirable to develop bioabsorbable and/or biocompatible polymers that extend the range of properties available.